Acrylonitrile-butadiene-1, 3 copolymers stabilized by antimonyl pyrogallolate



Patented Jan. 8, 1952 UNITED STATES PATENT OFFICE ACRYLONITRILE-BUTADIENE-L3 COPOLY- MERS STABILIZED B Y A N T I M NYL PYROGALLOLATE Harry E. Albert and George E. P. Smith, Jr., Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio No Drawing.

Original application March 30,

1949, Serial No. 84,493. Divided and this application May 29, 1951, Serial No. 229,532

2 Claims.

- ates, both cured and uncured, and the process of Sb OH antimonyl pyrogallolate HO Stabilization of Buna N-tz/pe synthetic rubbers Various tests are given below on different Buna N compounds showing the effect of the stabilizer of this invention and comparing the stabilizer of this invention with phenyl-beta-naphthylamine, the most widely used commercial product. Each of the stabilized compounds referred to was obtained by adding 2 parts of the stabilizer per 100 parts of copolymer to the latex resulting from emulsion copolymerization of acrylonitrile and 1,3-butadiene. The latex was then coagulated and dried, and the samples for tests on the vulcanizate were prepared by vulcanization of such dried coagulum. The hand tests given in the following table were made by pulling and feeling the copolymer to detect any stiffening or softening or other sign of deterioration.

The commercial stabilizers discolor Buna N- type rubbers badly, particularly on exposure to ultraviolet light. Most of the tests recorded, therefore, refer to change in color of the products and compare the color and color change with a control or blank. Table I refers to tests conducted on a copolymer obtained by copolymerization of 62 per cent butadiene and 32 per cent acrylonitrile.

TABLE I Copolymer stabilization After Drying at After Heat-aging 2 days at C.

Stabilizer Color Hand Test Color Hand Test antimonylpyrogallolate.v gray no deterigray good conoration. dition. pheiiily l-beta-naphthylabrown. .do brown. Do.

in e.

The above data show the antimonyl pyrogallolate to be as good as phenyl-beta-naphthylamine from the standpoint of preservation of plasticity and better from the standpoint of preservation of color.

The formulae given are illustrative. Different copolymers may be used, and with different compounding ingredients and difierent amounts of the stabilizer. In general it may be said that 0.1 to 10.0 parts of stabilizer on parts of copolymer, more or less, will give satisfactory results.

What we claim is:

1. A method of retarding the deterioration of acrylonitrile-butadiene-1,3 copolymers which comprises incorporating therein a small amount of antimonyl pyrogallolate.

2. A composition comprising acrylonitrile-butadiene-1,3 copolymer and a small amount of antimonyl pyrogallolate.

HARRY E. ALBERT. GEORGE E. P. SMITH, JR.

REFERENCES CITED UNITED STATES PATENTS Name Date Hunter Nov. 22, 1949 Number 

2. A COMPOSITION COMPRISING ACRYLONITRILE-BUTADIENE-1,3 COPOLYMER AND A SMALL AMOUNT OF ANTIMONYL PYROGALLOLATE. 